Models

A numerical model is being developed to simulate the influence of hydro dams, climate change, and irrigation on the hydrodynamics of the Mekong river and tributaries system.

The SWAT (Soil and Water Assessment Tool) model is being in partnership with MRC to derive water runoff for historical weather conditions and climate change. Erosion from catchments and sediment contributions to rivers are also being simulated with this model.

The HEC-HMS (Hydraulic Engineering Center - Hydraulic Modeling System by the US Army Corps of Engineers) is being trialed as an alternative to SWAT.

HEC-ResSim (Reservoir System Simulation) are being used to simulate the behavior of flows to reservoir and dam operations.

Sediment transport simulation capabilities is being added to the coupled SWAT and HEC ResSim models.

The HEC-EFM (Ecosystem Functions Model) will be used as a planning tool for analyzing ecosystem responses to changes in flow regime. This model will help link hydrological elements (season, flow frequency, duration and rate of change) to ecosystem function.

Hydrological Monitoring:

Hydrological changes over time can be monitored in two general ways:

a) direct and continuous measurements of flows and sediment or

b) by recording progressive (non-anthropogenic) changes

Future continuous monitoring recommendations will aim to identify key indicators of change including a program for long term monitoring of dam induced hydrological changes.

Vegetation and productivity:

Field surveys, remote sensing analysis, and ecological modeling will be carried out to quantify the importance of silt (nutrient) loads and flows to changes in productivity in the Tonle Sap. The results of this study will form a basis to understand the impact on other systems in the Mekong basin.

Land Cover Mapping:

Land-cover maps will be developed using standard digital classification protocols available in commercially available software packages (e.g., Leica-ERDAS) in combination with GIS models that incorporate other criteria such as slope, elevation, latitude, and soil type.

Natural vegetation types will be stratified according to physiognomic criteria that will incorporate information on above and below ground biomass, in order to provide an estimate of current carbon stocks and their potential value in a mechanisms for “Reducing Emissions from Deforestation and forest Degradation" (REDD).

To increase its utility as a modeling and monitoring data layer, we will estimate rates of past land-use change by sampling at least two dates in areas that have been identified as deforestation hotspots.

Changes in the hydrological regime are linked to changes in composition of flooding vegetation (flood forests, shrubland, grassland, agriculture), which subsequently are responsible for ecosystem productivity. As part of this project, we will aim to understand the significance of changes in sediment and flood regime on the Tonle Sap floodplain vegetation following development scenarios

Changes in ecosytems services will be weighed against economic benefits of dams operations and agricultural water abstractions. The potentail of a conservation corridor designed around the forest and habitat of the main tem of the Mekong floodplain will also be examined.

As W. Edwards once said "All models are wrong, some models are useful". We intend to make our models useful!